Artificial tooth



Aug. 31, 1943.

[Zap/2229;:

R. w. ERDLE 2,328,379

ARTIFICIAL TOOTH Filed April 10, 1940 Patented Aug. 31, 1943 Ait'rmcmi,'roo'ru Rainer W. lirdle, Chicago, Ill., assignor to Dental ResearchCorporation, Chicago, IlL, a corporation of Illinois Application April10, 1940, Serial No. 328,912

5 Claims.

' This invention relates to artificial teeth, and more particularly toan improved pinless retention therefor.. i

While pinless forms of retention for artificial teeth have beenpreviously proposed, the prior forms of pinless retention have not goneinto a general use because they have not been as practical as desired,and because it is impracticable to produce teeth of this type n therigid molds used by most manufacturers.

With pin retention, the pins have usuallybeen made of platinum, goldplated nickel, or the like, which makes the retention an expensivematter, not only on account of the material, but also on account of themany laborious operations required to produce pin teeth. Also, where apin retention is employed, the attachment of the tooth is localized, andthere is a tendency for the tooth to split at the point where the pinsare anchored when strain is applied to the tooth.

Another disadvantage of pin teeth is that in close bite cases, the pinsare'in the way, which interferes with the proper setting up of theteeth. Also, due to the fact that the pins have tobe anchored in thebulkiest part of the tooth, there is interference with the production ofa natural lingual aspect of the tooth.

In the case of applying stains to teeth in order to shade them to suitthe individual case. it is necessary to pass them through the iurnace tobakeon the stains. It is notpractic'able to do this with the ordinarypin teeth because the base metal pin will be oxidized. It has,therefore, been necessary to use platinum pin teeth which are expensiveand whichare not ordinarily carried in stock in dental supply houses.

Moreover, where pins are soldered into the teeth, if a high fusing stainis employed the high temperatures required may affect the solder or evenburn the gold plating oifof the pins. On the other hand, if a low fusingstain or glaze is employed, it is subject to attack by the saliva.

One of the main'obiects of the present invention is to provide animproved form of retention which is relatively inexpensive, dueparticularly to the fact that it makes it possible to dispense with pinsand the like and the laborious operations required to produce pin teeth;also, a formed retention which will secure the tooth firmly in. placeand with which the strengthof the tooth is greatly increased.

Another object of the invention is to provide a retention which isadapted to eliminate localization of the attachment of the tooth whichhas occurred with pin retentions, and which is also adapted toeliminate, when strain is applied to the tooth, the tendency of thetooth to split at the points where the pins are anchored in teeth withpin retention. I

It is also an object of the invention to provide a formed-retention thatwill permit an irregular set-up of the teeth to simulate naturalconditions; also, a formed retention that will minimize the risk ofexposing retention cavities and the like on account of such irregularset-up, and a formed retention adapted to avoid the problems of bakingon stains and the like where retention pins have been employed.

A further object of the invention is to provide an improved retentionwhich need not have pins or the like in the wayto interfere with thesetting up of the teeth, and which improved retention will lend itselfto the production of a natural lingual aspect of the tooth; also, animproved retention which will eliminate the difllculties heretoforepresented in passing teeth with pin retention through the furnace tobake on the stains for shading the teeth to suit the individual case.

1 Another object of the invention is to provide an improved form ofretention which will permit the denture base material toextend into thebody of the tooth and approach the incisal edge where the force ofbiting is applied, thereby allowing positioning of the retention closerto the point of application of the force than with pin retention, withconsequent less likelihood of the tooth coming loose.

Further objects and the precise features and advantages of the inventionwill be apparent from the following detailed description, taken inconnection with the accompanying drawing in which:

Figure 1 is a fragmentary front elevation showing two teeth with formedretention embodying 40 bodyingthe formed retention of the presentinvention on an enlarged scale; t

Figure 3 is a rear elevation of the tooth shown in Figure 2;

Figure 4 is a generally horizontal section taken on the line 4-4 ofFigure 3; Figure 5 is a front view of a posterior tooth embodying thepresent invention;

Figure 6 is a plan view of the tooth shown in Figure 5 on an enlargedscale; and

Figure 7 is a perspective view, partially broken away and in section,showing the details of the retention cavitiesand the generally V-shapedtegrally therewith. The surface 2| tongue-like portion 20 is inclinedfrom the upper edgeof the lingual surface I5 to the upper edge and 6,also on an enlarged scale.

Referring now in detail to the drawing, the reference character I(Figure 1) indicates frazmentarily a denture base or plate formed of anysuitable denture material. The teeth shown for purposes of illustrationat H and I2 are attached to the base or plate II) by molding'thedenturebase or plate material thereto, as well understood in the art.

While the retention of the present invention is not limited to anteriorteeth but may, within the broader aspects of the invention, be formed onposterior teeth as will hereinafter appear, the tooth II, which is shownin detail and on an enlarged scale in Figures 2, 3,. and 4, is one ofthe anterior teeth shown in Figure 1. Itmay be formed of porcelain, orany porcelain-likeor'other suitable tooth material, and is preferablymolded in a flexible mold in the mannermore fully described inmy'copending applicationySerialNo. 101,740, filed'September 21', 1936,now Patent No. 2,196,258, issuedApril 9,1940.

The use of .a flexible mold and the method of my above identifiedcopending "appll(=ation make it a simple matter to mold theteeth withthe retention of the present invention formed integrally therewith,thereby overcoming the obstacles to molding theteeth with this retentionin rigid mo1ds. It is-to;be"und erst0od, however, that I do not intendtov limit the tooth, and retention of the present invention *toformation in a flexible mold or by the method referred to, any suitablemold means and any s'uitablemethod of forming the tooth and retentionthereon being contemplated within the scope of the present invention.

The front or labial side of the tooth ii is indicated at I4, and therear or lingual side is indicated at 15. The front and rear surfaces l4and I5 are marked and of an extent to simulate the correspondingsurfaces of a natural tooth. The incisal edge of the tooth is indicatedat I5, and the opposite marginal edge of the front side of the tooth'maybe indented at I8 to enter the denture base material as shown in Figure1.

The back of thetooth has. a tongue-like portion or' generally I-shaped.rib 20 formed inof this of the front or labial surface I4. The tongue20 i is disposed substantially centrally between the opposite sides ofthe tooth and is of generally dove-tail'shape in horizontal section asshown in Figures- 3 and 4, with the wider end of the tonguedisposedinwardly or toward the rear side of the tootha'nd the generallyvertical sides 25 of the tongue converging outwardly to the narrower endof the tongue which is disposed outwardly or toward the front of thetooth.

The generally vertical retention surfaces 22 are preferably notcoplanar, but are inclined, as shown in Figure 4,. away from the labialsurface of the tooth. This permits-an irregular setup of the teeth tosimulate natural conditions, and 'minimizestherisk of exposing theretention cavi- .ties on account of such irregular setup. The 1 ,lowerends 6 the surfaces 22 extend down below ,t'neppper ed of the rear orlingual surface is, fl wher'e they meet the other sides 23 of the reten-;-'tion" cavities These other sides .23 .of the retention" cavities,one? of which is thus provided on each side of the 't ngue 20, mayfollow the curvaif -ture of the rear or lingual surface 15, or theyasaasve will be apparent that a retention cavity is formed on each ofthe opposite sides of the tongue-like portion 20 and that each of theseretention cavities has three sides. one side being formed by theadjacent side of the tongue 20 and the other sides being formed by theretention surfaces 22 and 23. These retention cavities are thus ofgenerally pyramidal form.

Each of the retention surfaces 25, 22, and 23 of each retention cavityhas a plurality of small serrations molded into the same. In theillustrated embodiment of the invention the retention serrations on theopposite sides of the tongue 20 are in the form of generally verticalgrooves 28, preferably with the grooves toward the front of greaterwidth for the easy flow of the base or plate material into the same. Theretention serrations on the retention surfaces 23 are shown in the formof grooves 29 inclined outwardly away from the opposite sides of thetongue 20; also, preferably with the grooves 29 toward the front-ofgreater width for the easy flow of the base or plate material into thesame. The retention means on the surfaces 22 are shown in the form ofgrooves 30 inclined upwardly from the opposite sides to the tongue 20.

The improved retentive effect of the formed retention of the presentinvention is dueto the combined influence of the. dovetail shape of thetongue-like portion 20 together with the effect of the many smallserrations which are molded into the surfaces of the retention cavity.In order to secure an additional degree of adhesion, the retentionsurfaces are all preferably sand blasted or otherwise treated to removethe glaze resulting from firing.

' The generally pyramidal shape of the retention cavities and theresulting generally pyramidal shape of'the denture base material as itenters and is molded into these cavities permit easy flow of the denturebase or plate material into the cavities when the denture is molded and,at the same time, the serrations produce an interlocking effect whichprevents the material from.

being pulled out again when force is applied to the tooth. The extensionof the retention surproach the incisal edge of the tooth where the forceof biting is applied. In this way, the retention is closer to the pointof application of the force than with pin retention, with consequentless likelihood of the tooth coming loose.v

In the posterior tooth shown in Figures 5, 6, and 7, the labial side isindicated at 40, the lingual side at-M, and the surface where the bitingforce is applied is indicated at 42. The surface of the tooth are shapedand marked to simulate the corresponding surfaces of a natural tooth, orotherwise as desired. r

The inwardly tapering retention cavities 43 extend inwardly into thebody of the tooth into relatively close proximity to where the bitingforce is applied at 42, and these cavities are sepascribed, and it is towhere the retention serrations are in th form the retention. Thesurfaces 48 of the cavities 43 have a plurality of small retentionserrations molded into the same, these retention serrations being shownin the form of grooves 50. As in the preceding embodiment of theinvention, the retention areas of the tooth preferably have the glaze,resulting from firing, sand blasted or otherwise removed therefrom.

The particular angle of the retention grooves shown in the drawing wasdetermined partly by tests of the efficiency of the retention and partlyby expediency in the production of the metal master teeth. Thearrangement shown is deemed entirely practicable, but it is to beunderstood that the angle of the retention grooves may be variedconsiderably from that shown and debe also understood that grooves maybe of the sawof grooves, these a different shape as, for intooth i typeor of stance, grooves of square cross section or of other form assuitable and desired.

With the present invention it is not necessary 7 to connect the tworetention cavities inside of the tooth so that the denture base materialcan actually come together from each side. The retention serrations inthe cavities cause the denture base material to become locked into thecavities, and, in combination with this, the dovetailed shape of thecenter tongue or rib is also effective in preventing displacement of thetooth in an interior direction when force is applied. Of courseundercutting of the center tongue or rib is contemplated as hereindisclosed.

In some instances it may be desirable to have the surfaces 22 curved inthe direction from gingival to incisal, and therefore such curvature iscontemplated within the scope of the present invention. It is alsopossible that it might be advantageous in some instances to curve thesesurfaces in the other direction, 1. e., from the median line of thetooth to the medial or distal, and that too is contemplated within thescope of the present invention.

I do not intend to be limited to the precise details shown or described.

I claim:

. 1. An artificial tooth having formed pinless retention moldedintegrally therewith and comprising a pair of generally pyramidal shapedretention cavities, a generally dovetail shaped rib between saidcavities, the front sides of said cavities being inclined away from thelabial surface of the tooth and generally vertically disposed,

said cavities being disconnected and the inner ends thereof extendinginwardly into the body of the tooth inwardly beyond the base of thelingual surface of the tooth and into relatively close proximity towhere the biting force is applied, a plurality of generally laterallydirected and inclined grooves molded into the front surfaces of saidcavities, generally vertical grooves molded into the opposite sides ofthe generally dovetail shaped rib, and retentiongrooves molded into theother sides ofsaid retention cavities.

2. A unitary artificial side retention denture tooth comprising a bodyhaving substantially complete labial and lingual surfaces and agenerally vertically disposed rib extending between said lingual andlabial surfaces and having a gingival surface sloping from the labialgingival downward to the lingual gingival, said rib decreasing in widthfrom said lingual surface toward said labial surface and defining withthe lingual and labial portions of the tooth body a at the labialsurface pair of substantially triangular retention cavities at oppositesides of said rib open at the sides of the body, each of said cavitiesbeing provided thereof with retention serrations extending outward fromsaid rib, the latter being provided at the opposite sides thereof withretention serrations. I

3. A unitary artificial side retention denture tooth comprising a bodyhaving substantially complete labial and lingual surfaces and agenerally vertically disposed rib extending between said lingual andlabial gingival surface sloping from the labial gingival downward to'thelingual gingival, said rib decreasing in width from said lingual surfacetoward said labial surface and defining with the ter being provided atthe opposite sides thereof 1 with retention serrations and each of saidrecesses being provided at the lingual surface thereof with retentionserrations substantially perpendicular to the serrations of said rib.

4. A unitary artificial side retention denture tooth comprising a bodyhaving substantially complete labial and lingual surfaces and agenerally vertically disposed rib extending between said lingual andlabial surfaces andhaving a gingival surface sloping from the labialgingival V downward to the lingual gingival, said rib decreasing inwidth from said lingual surface toward said labial surface throughoutits full height and defining with the lingual and labial portions of thetooth body a pair of substantially triangular retention cavities atopposite sides of said rib open at the sides of the body, each of saidcavities being provided at the labial surface thereof with retentionserrations extending outward from said rib, the latter being provided atthe opposite sides thereof with retention serrations disposedsubstantially perpendicularto said labial surface serrations and each ofsaid recesses being provided at the lingual surface thereof withretention serrations substantially perpendicular to the serrations ofsaid rib.

5. A unitary artificial side retention denture tooth comprising a bodyhaving substantially complete labial and lingual surfaces anda generallyvertically disposed rib extending between said lingual and labialsurfaces and having a gingival surface sloping from the labial gingivaldownward to the lingual gingival, said rib decreasing in width from saidlingual surface toward said labial surface throughout itsfull height anddefining with the lingual and labial portions of the tooth body a pairof substantially triangular retention cavities at opposite sides of saidrib open at the sides of the body, each of at the lingualsurface thereofwith retention ser-- rations substantially perpendicular to theserrations of said rib.

REINER W. ERDLE.

surfaces and having a

